Cathode locating and anchoring means for discharge tubes or the like



y 2 1941. w. L. KRAYHL 2,250,409

CATHODE LOCATING AND 'ANCHORING MEANS FOR DISCHARGE TUBES OR THE LIKEFiled March 2-9, 1940 '2 Sheets-Sheet 1 INVENTOR.

W Mi?" July 22, 1941. w. L. KRAHL 2,250,409 CATHCDE LOCATING ANDANCHORING MEANS FOR DISCHARGE TUBES QR THE LIKE Filed March 29. 1940 2Sheets-Sheet 2 A TTORNEYS.

Patented July 22, 1941 I CATEODE LOCATING AND ANCHORING' MEANS FORDISCHARGE TUBESOR THE LIKE .Walter L. Knoll, Swampscott, Mass, assignorto Hygrade Sylvania Co p ration, Emporium, la., a corporation ofMassachusetts Application March 29, 1940, Serial No. 326,571

8 Claims.

This invention refers to electric discharge devices and in particular toradio tubes with tubular electrodes such as cathode sleeves.

An object of the invention is to provide improved means for holdingtight at least one cross section of a tubular cathode by one of themembers which spaces the electrodes of an electrode in longitudinalarray and with a common coextensive cathode, together with improvedmeans for anchoring the cathode in the region between said assemblies. 7

A further object is to provide an improved manner of assembling a coatedcathode and of anchoring it intermediate its ends, without liability ofscraping the coating during assembly or use.

A feature of the invention relates to an improved unitary electrodespacer for radio tube mounts and the like, arranged to be permanentlyfastened to one or more electrodes such as through the plate supports orthe like, and which is provided with an integral flexible tongue forclamping the cathode.

Another feature relates to an improved method of mounting and anchoringcathodes having a plurality of discrete coated sections.

Other features and advantages not specifically v enumerated will beapparent after a consideration of the following detailed descriptionsand the appended claims.

In a large number of types of radio tubes, the mount includes'a tubularcathode which is surrounded by one or more grids and a plate. Theseelectrodes are spaced at their ends by the top and bottom mount spacer,usually made up of a disc-shaped or rectangular piece of mice sheet,provided with holes for receiving and spacing the supports or side rodsof the electrodes. Some of these holes may be provided with eye letinserts to which at least two of the support members are welded, so asto insure that all the electrodes are firmly enclosed between the topand bottom mount spacers. Some of the support wires may be sealedthrough the stem or header, on which the tube is mounted. Others may beheld in place by the mount spacers only, and are metallically connectedto the stem leads (or to a top lead) by means of connectors, which maybe welded to the short pieces of the electrode supports protruding fromthe holes in one of the mount spacers either at the top or at thebottom. The ends of the tubular cathodes may be provided with beads inorder to prevent them from sliding through the holes in the mountspacers.

There are different ways of mounting or assembling the electrodes. Anelectrode-system may be completely assembled between two mount spacers,forming a rigid unit, and later on be fastened to the leads of a stem orheader. 01, two of the stem leads may be developed or extended assupports for one of the electrodes (usually of the plate). In this case,the bottom mount spacer is first inserted into these leadsupports andfastened to them. The electrodes are then inserted into the holesprovided for them in the mount spacer, and the top mount spacer is thenassembled over the upper end of the electrode supports and fastened tothem. Finally, those electrodes which are not yet metallically connectedto their respective stem- (or top-) leads are then welded to specialconnectors, in the form of pieces of metal strip or wire, and the'otherends of the connectors are welded to the corresponding leads, asdescribed above. In diode-triodes, diode-pentodes, triode-hexodes andother multi-sectional tubes, especially where the sections are mountedin longitudinal array, the cathode is frequently coextensive with andcommon to both sections, and it is often necessary to provide anadditional, (third) mountspacer, between the top and bottom mountspacer, which additional spacer is provided with the holes necessary tospace the electrodes near that part of the mount Where one of the twosections of the tube ends and the other begins. The hole provided forthe cathode in the intermediate mount spacer must, of course, be largeenough to let the cathode pass freely, in order to avoid scraping of theemitter coating when the cathode is inserted.

It has been found thatit is desirable to give a support to the cathodein the intermediate mount spacer,-in order to avoid microphonism.Several methods have been used to attain this objective, but they areeither expensive, or do not avoid the scraping of the emitter coating.

The present invention avoids all these disadvantages, and insures apositive locking of the cathode by one or more of the spacers. By meansof the. invention it is even possible in certain cases, as indiode-triodes and diode-pentodes,

to eliminate the bottom mount spacer altogether,

without any sacrifice of mechanical strength or concession tomicrophonism.

The objects and features above enumerated are carried out by means of aspecifically shaped intermediate mount spacer, into which the uncoatedpart of a cathode separating the two coated parts, can be introducedwithout threading the cathode through the hole which locks the uncoatedpart of the cathode to this mount spacer. In mounting a tube, thecathode and the mount spacer are fitted together before the mount spaceris attached to the mount supports. In other cases, grids and plates ofan amplifier section may be secured to the mount spacer, in addition tothe cathode, before the spacer is fastened to the mount supports.

In the attached drawings which illustrate the invention.

Fig. 1 is a top-plan view of a spacer and anchoring member according tothe invention.

Fig. 2 is a front-edge view of Fig. 1.

Fig. 3 shows a modification of Fig. 1.

Figs. 4a, 4b and 4c, illustrate successive steps in assembling a cathodesleeve into the spacer of Fig. 1 or Fig. 3. I

Fig. 5 shows one well-known form of tube mount embodying the invention.

Fig. 6 shows another well-known form of tube mount embodyingtheinvention.

Referring now to Figs. 1 and 2, which show top and side views of the newmount spacer I made of a thin sheet of mica or the like, numerals 2, 3,8, 1, indicate holes into which the grid andplate supports or side rodsof a triode section of a radio tube are threaded for spacing theelectrodes. More holes may be provided for tubes containing a largernumber of electrodes and mount supports or side rods.

In most of the conventional radio tube mounts, the cathode is spacedfrom'the other electrodes by a hole at or near the center of gravity ofthe mount spacers. The hole (8) which is designed to hold the cathode inthe new spacer is "made slightly smaller than the diameter of thecathode sleeve, and is continued by slots 4 and 5 thus providing aresilient tongue B which may be slightly tilted out of the plane of thespacer I approximately along an axis I indicated by a dotted line inFig. 1, and as shown more clearly in Figs. 2, 4a and 4b.

In order to insert the cathode sleeve ill (Fig. 4b) into the hole I, theuncoated intermediate portion C is placed at the entrance D of slot 4,and the tongue B is slightly pressed out of the plane of the mountspacer as shown in Figs. 2. 4a and 4b. The cathode is held at a smallangle with respect to the mount spacer, and the cathode as a whole ismoved along the slot 4 in a direction substantially parallel to theplane of spacer i and finally inserted into the hole I. Care is to betaken that the uncoated portion 0 of the cathode stays between themargins oi slot 4 during this motion.

When the cathode has'reached hole I at the end of the slot 4, it istilted into its final position perpendicular to the plane of the mountspacer as shown in Fig. 4c. The hole I has a diameter slightly smallerthan the outer diameter of the cathodesleeve, and the cathode istherefore prevented from sliding through the hole as well as from movingin the plan of the mount spacer by reason of the resilient clamping orgripping effect between the tongue B and the remaining peripheral edgeof hole I.

Depending on the particular construction and used to cut vthe spacer.

the type of the tube, the unit composed of the cathode and the new mountspacer as shown in Fig. 40, may now either be inserted in and fastenedto the main supports of the stem or header, or it may be advantageous toinsert the grids and plate of the upper section of the mount into thenew mount spacer before fastening the spacer to the main supports.

For the type of tube mount illustrated in Fig. 5, it is advantageous toinsert grid II and plate i'l into the mount spacer before fastening themount spacer in its final position E on the main supports II and I2above the previously mounted diode-plates and shield. Fig. 5 shows adiodetriode of the lolrtal type, in which all the leads are brought outthrough the stem-base or header l8 as described in detail in applicationSerial No. 189,295. As the space between the diode shield l3 and thegrid and plate supports II and i2, sticking out from under the mountspacer I in its postion E is very limited, it is preferred to weld the.grid and plate connectors Ila and Ila to their respective electrodesbefore the mount spacer is inserted into the main supports II and I2.

In mounting the diode-triode shown in Fig. 6, in which the grid leadgoes through the top of the bulb. and the plate is fastened directly tothe main supports, the grid may be inserted either before or after theunit shown in Fig. 40 has been fastened to the main supports II and 22.The plate of such a tube must, of course, be inserted after the mountsupport is in its final position E.

The examples illustrated in Figs. 5 and 6 are diode-triodes. ing apentode-diode or a triode-hexode with the new mount spacer are similarand need not be described in detail.

While the spacer of Figs. 1 to dis primarily advantageous in so-calledmulti-sectional tubes, it will be clear that it also has advantages whenused in single-section tubes such as diodes, trlodes, pentodes, etc.Thus the conventional upper or lower mica spacer used in suchsinglesection tubes, can be replaced by a spacer like that of Fig. 1 or3.

While in Figs. 1 to 3, certain relative dimensions of the various holesand slots are shown, it will be understood that they are merelyillustrative. Thus, the slots 4 and I may be as narrow as canconveniently be arranged while allowing the necessary strength to thedie which is The slot I preferably terminates in the hole II, the sizeand shape of which is designed to avoid any tendency for ripping orcracking of the spacer when the tongue B is bent as shown in Figs. 2, 4aand 4b. The hole 23 also enables the cutting die to be strengthened atthe corresponding end thereof.

Furthermore, while the drawing shows the slot 4 at right angles to thespacer edge, it will be understood that this is not necessary and theslot 4 may be at any suitable angle. While the spacer above describedmay provide sumcient clamping to prevent lomritudinal displacement,

'it is usually desirable to add other securing means, such as beads, asdescribed in Patent No. 1,974,916 or pinching theends of the cathode. Inthis case of course, the sire of the hole I will be slightly less thanthe peripheral circumference at the base of the groove so that thespacer firmly grips the cathode sleeve and is at the same timemechanically interlocked therewith. While one particular configurationof spacer is shown. namely one which is substan- The steps necessary formounttially rectangular, any other shape such as circular, elliptical orthe like maybe employed.

From the foregoing, it will be seen that among other advantages of theinvention, there is an increased tightness of the connection between thecathode and the remaining elements of the mount, and since there is noplay between the cathode and the spacer, a more exact spacing relationbetween the cathode and the other electrodes can be maintained.Furthermore, the assembly of the cathode in the mount is simplilied andthe liability of scraping the emission coating is avoided. As a result,a considerable saving of cost in the manufacture and assembly and thereduction of shrinkage are achieved. Finally, the assembly such as shownin Figs. and 6, provides a tube which in operation is singularly freefrom microphonic noises and the like.

Various changes and modifications may be made without departing from thespirit and scope of the invention. Thus, while the invention has beenillustrated with one hole 8 and tongue B, a plurality of such holes andtongues may be provided where more than one cathode is employed, orwhere it is desired to anchor some other element such as a grid supportin addition to, or in place of, the cathode. Furthermore, the spacer perse is applicable to any other device where a conductor is desired to bemaintained in spaced relation to another surrounding member orconductor.

What I claim is:

1. A spacer device comprising a substantially planar insulator memberhaving a slot in one edge terminating in a hole to receive an element tobe electrically spaced from another element,

means to support said cathode comprising a substantially fiat sheet ofinsulation having an opening to receive said cathode and to grip itintermediate its ends at said uncoated area. and a slot extending froman edge of said sheet to said opening whereby said cathode can be in andspace said cathode from said surrounding electrode including a sheet ofinsulation having an integral tongue said tongue defining .with an edgeof said sheet an opening slightly smaller than' the cathode acrosssection whereby said cathode is firmly gripped intermediate its ends,and means to'fasten said sheet to said uprights.

7. An electron tube mount comprising a. pair of electrode assembliesmounted in longitudinal array, a common cathode extending through said jassemblies and means to grip and support said said slot dividing saidmember into at least one tongue portion which is defiectable out of theplane of the member.

2. A spacer device comprising a generally fiat insulator member havingan edge slot and an interior slot in communication with each other todefine a defleetable gripping tongue and an opening to receive anelement to be spaced from another element.

3. A spacer device according to claim 2, which is of mica and the saidslots are substantially at right angles to each other.

4. In combination, a cathode having a coated and an uncoated. area alongits length, and

cathode in the region between said assemblies, the last-mentioned meansincluding a substantially planar insulator having an opening to receivesaid cathode, and an integral flexible tongue portion having an edgedefining part of said opening, said opening being slightly smaller thanthe cross section of the cathode at the region where it is gripped.

8. The method of assembling a cathode sleeve into an insulator spacermember of the typehaving a slot defining a deflectable tongue and acathode receiving opening which comprises, positioning the sleeve withits length transverse to the plane of said spacer, deflecting saidtongue out of the plane of said spacer, producing relative motionbetween said cathode and said spacer, substantially parallel to.theplane of said spacer and along said slot until said cathode enters saidopening and then allowing said tongue to spring back to its normalposition whereby it firmly grips said sleeve.

WALTER 1.. KRAHL.

